1. Field of the Invention
The present invention relates to a surveillance camera apparatus, and more particularly to a surveillance camera apparatus partially constituting a surveillance system for watching a specific object such as for example unqualified people and other intruders intruding into a special room that does not permit people without permission to enter.
2. Description of the Related Art
Up until now, there have been proposed a wide variety of conventional surveillance camera apparatus comprising a housing assembly having an opening, and a camera assembly accommodated in the housing assembly, the camera assembly taking an image of a specific object through the opening of the housing assembly.
One typical example of the conventional surveillance camera apparatus 100 of this type comprises a housing assembly 180 and a camera assembly 125 accommodated in the housing assembly 180. The housing assembly 180 is shown in FIG. 13 as including a slanted plate portion 121 defining a circular opening 185 having a central axis 135, a hollow hemispherical portion 130.
The camera assembly 125 is shown in FIG. 11 as including a stationary member 126, a pan shaft 140 having a pan axis “A” perpendicular to a horizontal plane 190, the pan shaft 140 being supported by the stationary member to be revolvable around the pan axis “A”, a retaining member 109 integrally formed with the pan shaft 140, a tilt shaft 150 having a tilt axis “B” thereof, the tilt shaft 150 being retained by the retaining member 109 to be revolvable around the tilt axis “B” under the state that the tilt axis “B” of the tilt shaft 150 is in perpendicular relationship with the pan axis “A” of the pan shaft 140, an imaging unit 110 for taking an image of a specific object through the opening 185 of the slanted plate portion 121 forming part of the housing assembly 180, the imaging unit 110 having a light axis 129 thereof, the imaging unit 110 being integrally supported by the tilt shaft 150 under the state that the light axis 129 of the imaging unit 110 is in perpendicular relationship with the tilt axis “B” of the tilt shaft 150.
The camera assembly 125 further includes a pan motor 160 for having the pan shaft 140 driven around the pan axis “A”, a tilt motor 170 for having the tilt shaft 150 driven around the tilt axis “B”, and a controlling unit 120 for controlling the pan motor 160 to have the imaging unit 110 move around the pan axis “A” of the pan shaft 140, and controlling the tilt motor 170 to have the imaging unit 110 move around the tilt axis “B” of the tilt shaft 150.
The controlling unit 120 is shown in FIG. 12 as including pan signal producing means 161 for producing a pan signal in association with the revolution of the pan shaft 140, pan value calculating means 165 for calculating a pan value indicative of the pan angle “θp” in response to the pan signal produced by the pan signal producing means 161, tilt signal producing means 171 for producing a tilt signal in association with the revolution of the tilt shaft 150, and tilt value calculating means 175 for calculating a tilt value indicative of the tilt angle “θt” in response to the tilt signal produced by the tilt signal producing means 171.
The controlling unit 120 further includes upper-limiting pan value storing means 164 for previously storing a predetermined upper-limiting pan value “Θpmax”, pan motor controlling means 163 for controlling the pan motor driving means 162 to have the pan motor driving means 162 drive the pan motor 160 in response to the predetermined upper-limiting pan value “Θpmax” received from the upper-limiting pan value storing means 164 and the pan value calculated by the pan value calculating means 165, and pan motor driving means 162 for driving the pan motor 160 to have the driving shaft of the pan motor 160 move around the central axis of the driving shaft of the pan motor 160.
The controlling unit 120 further includes upper-limiting tilt value storing means 174 for previously storing a predetermined upper-limiting tilt value “Θtmax”, tilt motor controlling means 173 for controlling the tilt motor driving means 172 to have the tilt motor driving means 172 drive the tilt motor 170 in response to an operation command signal received from a microcomputer unit through an input terminal 176, the predetermined upper-limiting tilt value “Θtmax” received from the upper-limiting tilt value storing means 174 and the tilt value calculated by the tilt value calculating means 175, and tilt motor driving means 172 for driving the tilt motor 170 to have the driving shaft of the tilt motor 170 move around the central axis of the driving shaft of the tilt motor 170.
The conventional surveillance camera apparatus constructed as previously mentioned is securely supported by, for example, a ceiling wall partially forming a special room to watch the specific object such as for example unqualified people and other intruders intruding into the special room that does not permit people with any permission from entering.
In order to have the imaging unit 110 move around the pan axis “A” of the pan shaft 140, the microcomputer is operated to output the operation command signal to the controlling unit 120. The operation command signal is firstly received from the microcomputer unit through the input terminal 166 by the controlling unit 120. The pan motor driving means 162 is then controlled by the pan motor controlling means 163 to have the imaging unit 110 move around the pan axis “A” of the pan shaft 140 in response to the operation command signal received from the microcomputer unit through the input terminal 166, the pan value calculated by the pan value calculating means 165, and the predetermined upper-limiting pan value “Θpmax” received from the upper-limiting pan value storing means 164.
The pan motor driving means 162 is then controlled by the pan motor controlling means 163 to have the imaging unit 110 move around the pan axis “A” of the pan shaft 140 when the judgment is made by the pan motor controlling means 163 as the pan value calculated by the pan value calculating means 165 being smaller than the predetermined upper-limiting pan value “Θpmax” received from the upper-limiting pan value storing means 164. The pan motor driving means 162 is, on the other hand, controlled by the pan motor controlling means 163 to have the imaging unit 110 fail to move around the pan axis “A” of the pan shaft 140 when the judgment is made by the pan motor controlling means 163 as the pan value calculated by the pan value calculating means 165 being not smaller than the predetermined upper-limiting pan value “Θpmax” received from the upper-limiting pan value storing means 164.
Referring to FIG. 14 of the drawings, there is shown a graph showing the predetermined upper-limiting pan value “Θpmax” in association with the tilt angle “θt”, the broken line 200 indicative of each of the upper-limiting pan value “Θp” and the upper-limiting tilt value “Θt”, a first straight line passing through the point “R1” and the point “R2”, a second straight line passing through the point “R1” and the point “R8”, a third straight line passing through the point “R2” and the point “R9”, a region defined by the broken line 200 and the first to third straight lines. The upper-limiting pan value “Θp” and the upper-limiting tilt value “Θt” each depends on the shape of the opening 185 of the slanted plate portion 121 and the slanted angle “θo” at which the inner surface of the slanted plate portion 121 is in face-to-face relation ship with the inner surface of the vertical plate portion.
If the imaging unit 110 is moved into the region defined by the broken line 200 and the first to third straight lines as previously mentioned, the slanted plate portion 121 of the housing assembly 180 functions to prevent the imaging unit 110 from taking the image of the object.
The conventional surveillance camera apparatus thus constructed as previously mentioned, however, encounter such a problem that each of the pan motor and tilt motor is controlled by the controlling unit to have imaging unit move around each of the pan axis of the pan shaft and tilt axis of the tilt shaft without taking account of the slanted angle and the shape of the opening of the slanted plate portion of the housing assembly. This leads to the fact that the slanted plate portion of the housing assembly tends to function to prevent the imaging unit from taking the image of the object. As a result of the fact that the slanted plate portion of the housing assembly tends to prevent the imaging unit from taking the image of the object, the slanted plate portion of the housing assembly makes it impossible for the surveillance system to watch a specific object such as for example unqualified people and other intruders intruding into a special room that does not permit people with any permission from entering.